1. Field of Invention
The present invention relates to an electromagnetic shielding device and a method for fabricating the same, and more particularly to an electromagnetic shielding device using conductive rubber as the frame thereof and a method for fabricating the same.
2. Description of the Related Art
One of common problems with an electronic equipment is electromagnetic interference (EMI). A running circuit usually emits electromagnetic radiation, which affects the transmission signals and electric performances of other electronic components. A mobile phone, for example, has a strict requirement on anti electromagnetic interference (anti-EMI), due to a quite fast transmission speed the mobile phone's signal has. Therefore, in general, a mobile phone is always equipped with an electromagnetic shielding device (ESD) on the printed circuit board (PCB) thereof to prevent the electromagnetic radiation from leakage or to avoid an induced in leakage of external electromagnetic radiations, which causes unwanted interferences.
FIG. 1A is a cubic exploded drawing of a conventional electromagnetic shielding device. FIG. 1B is a cubic drawing of the electromagnetic shielding device in FIG. 1A after assembling. Referring to FIGS. 1A and 1B, a conventional electromagnetic shielding device 100 is made of metal material and includes a metallic frame 110 and a metallic cover 120. The metallic frame 110 is fixed on a PCB 130 by using surface mount technology (SMT) and has multiple protrusion portions 112 on the outer surface 110a thereof. The metallic cover 120 has a cover plate 122 and a side wall 124, which joins the periphery region of the cover plate 122 has multiple through holes 126 corresponding to the above-mentioned protrusion portions 112.
To assemble the metallic cover 120 onto the metallic frame 110, the inner surface of the side wall 124 of the metallic cover 120 is fit on with the outer surface 110a of the metallic frame 110, followed by buckling the protrusion portions 112 on the metallic frame 110 in the corresponding through holes 126 of the metallic cover 120, so as to reliably assemble the metallic cover 120 with the metallic frame 110.
Since the metallic cover 120 and the metallic frame 110 are closely interconnected by means of the above-described approach, the metallic cover 120 is unlikely separated from the metallic frame 110. In turn, the metallic cover 120 is accordingly hard to be disassembled from the metallic frame 110 when the electronic components on the PCB 130 need to be maintained. As a usual maintain manner today, some hand tools, such as tweezers, are used to prize the side wall 124 of the metallic cover 120, followed by removing the metallic cover 120 from the metallic frame 110. However, during removing the metallic cover 120 from the metallic frame 110, the side wall 124 of the metallic cover 120 are likely deformed and then the metallic cover 120 is hard to keep its original shape for using repeatedly. Besides, during disassembling the metallic cover 120, the integrity of the outer surface 110a of the metallic frame 110 is further destroyed. For a metallic frame 110 fixed on the PCB 130 by using surface mount technology (SMT), an accidental operation mistake resulting in integrity loss of the metallic frame 110 may further cause assembly troubles after maintaining.
On the other hand, it needs to take account of material cost issue. For a usual electromagnetic shielding device today, the cover and the frame thereof are made of metal. To get better metal conductive efficiency, copper is a preferred choice for the cover and the frame. However, in recent years, the prices of metal material together with most of crude material, particularly the price of copper, has been soaring continuously, which further increases the production cost of an ESD to impressive extent.